


A Brief Encounter

by Alex-writes-about-life (Alexwritesaboutlife)



Series: Soulmate AU Undertale [4]
Category: Undertale (Video Game)
Genre: Alternate Universe - Flowerfell, Alternate Universe - Soulmates, Alternate Universe - Swapfell, Alternate Universe - Underfell, Alternate Universe - Underlust, Alternate Universe - Underswap, Angst, Angst with a Happy Ending, Classic Sans - Freeform, Drunk Sans, F/M, Flowerfell sans, Fluff, Fluff and Angst, Happy Ending, Hugs, Jealous Sans, Kisses, M/M, Multiple Sans', Multiverse, Nerdy Sans, Poor Sans, Protective Sans, Romantic Soulmates, Sans Needs A Hug, Sans has glasses, Sleepy Cuddles, Soulmate-Identifying Marks, Swapfell Sans, Underfell Sans, Underlust Sans - Freeform, Underswap Papyrus, Underswap Sans, idk - Freeform, other stuff probably, sans is cute
Language: English
Status: In-Progress
Published: 2016-07-20
Updated: 2017-05-10
Packaged: 2018-07-25 17:22:15
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 6
Words: 14,567
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7541395
Author URL: https://archiveofourown.org/users/Alexwritesaboutlife/pseuds/Alex-writes-about-life
Summary: <blockquote class="userstuff">
              <p>You and Sans are scientists and you've been appointed to investigate soulmates! But...some things in this world aren't meant to be tampered with, and true love is one of them!</p><p>Requests, asks and submissions open at http://alex-thinks-about-life.tumblr.com/!!!</p>
            </blockquote>





	1. The science of soulmates

**Author's Note:**

> Guess who's back, back again? It's me the Trash Queen! Huzzah! Hope you guys enjoy this thing, I had the idea for it this morning!!

“Are you sure about this Sans?” You peered at the machine through the murky lenses of your goggles. You’d tried wiping them off but it didn’t seem to help. You had only begrudgingly donned the oversized pieces of plastic, arguing that you weren’t dealing with chemicals, so the use of goggles was redundant, after Sans reminded you that anything could potentially go wrong once you activated the machine. Since you were in essence about to try and take apart some of the material magic of the universe, it was possible it could cause some debris and he’d feel safer if you had a piece of plastic between said debris and your ‘delicate human eyes’. 

When that didn’t work, he reminded you Dr Gaster might pop in to survey the experiment. That got the goggles on faster than you could say science. Something about Dr Gaster unnerved you, and you really didn’t want to give him any excuse to scrutinise you. 

The machine you were both currently focused on, was a device, meant to analyse the magic which caused soulmates. You had managed to analyse the outcome of the soulmate equation, including factors like the likelihood of meeting, soulmates becoming deceased etc., but it was difficult to analyse properly without looking at the magic itself. 

Doing so could allow you to answer many of the big questions, such as why people were considered compatible by the magic, why some people were ‘blank canvases’ without soulmarks, and why some people had multiple. Why some people were born without soulmarks but could later receive them. 

The two of you had been lab partners for a while before being elected for this project. You liked Sans, he was funny and nice, although maybe a bit too laid back for the importance of the work you often had to do. Nevertheless, the two of you had shared more than a few jokes and bonded quite well. You had met his brother, Papyrus, who was loud and initially seemed quite arrogant. But after spending time with him, you learnt all Papyrus craved was popularity, but that he valued his friends to the extent where merely having a few felt like being popular. You could relate to that. You didn’t have many friends but the few you did have could make you feel on top of the world. You could see Papyrus made Sans feel the same way. Papyrus was proud of Sans for leaving the house every day. For getting a job that wasn’t an illegal hot dog stand. For not slacking off. 

As you understood it, Sans had mild depression. It had been far more severe before you had met him, when they were still trapped. Once they had gotten to the surface, through combined efforts Papyrus and another individual by the name of Toriel had convinced (or forced) Sans to go to a therapist. Whilst initially resistant to the treatment, it seemed the more time went past, the more Sans would relax and co-operate with his therapist. He had been very welcoming when you arrived, a trait you weren’t expecting when Dr Gaster told you he could be on edge around humans. You took a personal pride in being able to make him laugh. It was oddly satisfying.

You sometimes had to prompt him to eat, but it happened less often now, although Papyrus would always send him with a lunch, so if he tried to say he forgot lunch you knew he was lying. Even if he hadn’t any you would have bought it for him.

Regardless, you wouldn’t have wanted anyone else to be your partner for this project. 

You had been elected because you were the most suitable candidates for the experiment. Sans was a blank canvas, or at least he claimed to be, so if something with the magic went wrong, somehow affecting your soulmarks, he would be unaffected. You often wondered if it bothered him being a blank canvas, but whenever you asked, he merely chuckled and waved it off, remarking “’d take a lot more than that to rattle my bones kid.” 

You weren’t a blank canvas. Your mark was there, clear as day, cursive curling down the inside of your arm. The reason you accepted the assignment was because of the mark. Standing in little ridges along your arm were the beautifully romantic words your soulmate would first say to you. ‘Who the fuck are you?’ 

Yes, it was selfish of you to accept the mission. If something went wrong, it might not just affect you, but your soulmate as well. However, you accepted the risks when you were debriefed, and you were willing to substitute your own happiness to further the understanding of soulmate magic. Besides, you had always had a sneaking suspicion that you might be one of the rarer unrequited soulmates. It would be just your luck. You had, just like everyone else, spent many years looking for your soulmate. Your search had been reinvigorated after monsters emerged from the Underground.

And so it was that your partner turned to grin at you, mad scientist mode engaged. His glasses were taped to the side of his head, refusing to don the ridiculous goggles, or rib-diculous as he called them. The oversized glasses were adorable on the short skeleton, although the tape made him look just as ridiculous. His lab coat sleeves were rolled up to the elbows, and it was only due to Toriel’s generosity and skill with a needle that either of you were able to wear the coat without stepping on the hems. He stood a few inches shorter than you, so you felt justified in your accusation, however it was a cause of great despair for you when the excessively tall Dr Gaster nicknamed you Short and Shorter.  
“You ready, bud?” He asked, ignoring your question, and leaving you unsure as to how certain he was that this would be a good idea. A lazy grin on his face, not quite hiding the giveaway twinkle in his eye which always appeared whenever science was involved. Not wanting to delay proceedings any longer than possible, you gave him a thumbs up.  
“Let-er rip Sans!!” 

The small skeleton moved fluidly to the machine, placing his hand on the top of the giant lever. In one swift motion he pulled it down, almost to the floor of the room. 

The machine released a quiet hiss, and began to rumble. You both grinned widely as the machine began to produce results, automatically recorded by the small machine next to it. 

Everything was going to plan. 

Until Sans let out a yelp and whipped his hand away from the top of the machine, frantically shaking his hand to cool it down. The machine shouldn’t have been able to overheat; you had included some of the strongest coolant you had in the machine. And yet the steam coming from the machine was a clear sign that something was not right.  
Frantically the two of you fussed over the machine, in a desperate attempt to locate the source of the problem, when Sans yelled “Get back!” You jumped backwards in confusion, still focused on the machine until, it exploded. 

Well, rather it imploded, all the matter being sucked into some form of rip that seemed to materialise where the machine had been. It was dark black, and seemed to shimmer with rainbow colour like the surface of oil in the sun. It was swirling with colour and you could feel powerful magic inside the crevice. Had the two of you been standing an inch closer you would have been sucked in. You could feel the pressure from where you were standing, and you had to keep walking backwards to stop yourself from being sucked in. The pressure on your person was immense and you winced at the hard tug on your body. 

“Sans! What do we do?!” You cried. He opened his mouth to respond when suddenly the pressure stopped. You sighed in relief and opened your mouth to ask what happened, when you heard Sans curse softly. 

“Oh shit.” Before you had time to ask, you were hit by an invisible force, which you identified as magic, throwing you across the room, and almost striking your head on the wall. 

You were stopped last minute by a new force, a kind of magic which cushioned your fall. You looked up to see Sans, eye alight with blue magic, slippered feet planted on the ground, hand extended towards you, and your soul floating a few inches in front of your chest, coloured a dark blue. You glanced towards his face, a look of intense concentration furrowing his features. His eye met yours. 

“Are you alright?” He asked.

You nodded and with that reassurance he lowered you to the ground and turned his attention towards the ball of red magic which stood in the middle of the room at the centre of the explosion. This was the source of the magic which had sent you flying backwards, and was inexplicably attacking everything in sight. There was an aggressive feeling to the magic and you were very glad for your study of magic when you were training for the position. You prided yourself on being quite skilled at reading magic, which was one of the factors in your inclusion on the project. You could feel Sans’ magic, scared, cautious and with the typical underlying personality traits of the user. The red magic was angry but there was a sense of fear and defensive instinct threaded through it. There was also an odd sensation to the magic. It was very similar to Sans’, some of the base characteristics too similar. Your brow furrowed, but you assumed it was the effect Sans’ magic was having on the others.  
The two mixed together in some kind of mad, intoxicating tango into a deep violet. You could feel Sans focusing on the feeling of fear and anger, exerting his own natural calmness. 

Eventually it seemed that Sans’ magic gained the upper hand and began to force the magic back into the orb surrounding the user at the centre of the magic storm. Gradually the traces of magic faded from the room, and the red sphere dissolved.  
There, stood in the centre of the set of circular scorch marks, one eye lit with a red pupil, while the other was void of all light, was a very angry, sweaty looking …Sans? 

The resemblance was too striking to be co-incidental. The same rounded skull, and stocky figure, although the Sans in the middle of the room seemed a few inches taller than you. There were a few differences between the two, the angry Sans wearing red sneakers, with mustard yellow socks where Sans’ feet were donned by only a pair of pale pink house slippers. 

The other Sans’ socks were pulled up high, as though he wanted as little bone to be on show as possible. Both had almost identical shorts, Sans’ navy with a singular white stripe, whilst red Sans had black with two yellow stripes, one thick and one thin in a pair of parallel lines. 

A thin baggy white top hung loosely from Sans’ bones, exposing the tops of his clavicle, and a thick blue hoodie slung over the top, a huge mound of white fluff reaching his cheek bone. His white lab coat was covering the rest of the outfit, the bottom of it singed black by the force of the explosion. He wore the same outfit every day so it wasn’t much of a struggle for you to recall it. The layers were required to keep his oversized lab coat on his bones due to the lack of skin and muscles. His face, usually in a calm smile, was contorted by worry, annoyance and a little nervousness. 

Red Sans wore a plush red turtleneck, the neck pulled up under to his chin, and a thick black hoodie, with a yellow zipper and lined with thick fur, similar to that lining Sans’ hood, although it looked unrulier and could be seen lining the sleeve as it poked out around his wrists. These facts seemed to concur with your suspicion he wanted to cover as much bone as possible, as though they were a kind of armour. The most disconcerting difference was his teeth though. Whilst red Sans’ mouth was pulled back into a snarl, his teeth were sharpened into points, and a single golden tooth stood out from the crowd of pearly whites. 

His eyes seemed to be flickering all around the room, observing you, Sans, the equipment, but he seemed distracted by you, something which caught you off guard when he growled out his first words. 

“Who the fuck are you?”

 

You stiffened in shock. That was unexpected. You had been expecting a best case scenario of collecting some good data and a worst case scenario of losing your own soulmate. 

Instead, your machine had been sucked into some kind of trans-dimensional rift, you had gotten barely any data, and been attacked by Sans’ edgy twin who apparently was also your soulmate. 

Okay. You could feel yourself paling as you turned to look at Sans, whose eye sockets were wide with shock, as his lights flickered to your face. He knew what your soulmark said, and apparently this development had rendered the otherwise stoic skeleton shocked for the first time in this incident.

“Sans?” You whispered. “What happened and why is your twin currently standing where the machine was?”

“He ain’t my twin. Wish it were that simple. Nah he’s me from another universe.”  
Okay what? “You mean like…an alternate universe?” You asked. 

“Basically. You’ve heard’ve the multiverse theory right?” You nodded. “Well, he’s an alternate version of me. There’s lots of ‘em out there but I’m guessin’ he’s here cause of you.” 

“Because of me?” 

“Right. Soulmark and all. Since we were fiddlin’ with the soulmate magic, it makes sense.” Ah. That did make sense. 

Meanwhile, Red Sans was still stood in the middle of the scorch circle, eyes switching from you and Sans in a confused manner. 

“Scuse me!” He yelled, his frustration apparently reaching its peak. “Will you please, (this was directed at Sans) explain what the fuck I’m doin’ here? An’ who the fuck are you?” He demanded of you. 

You cleared your throat as you turned to face Red Sans. “My name is Y/N. Y/N L/N. Pleasure to meet you.” 

You had half hoped he might not have a soulmark, that he might just accept that fact and move on. But his sockets widened and his mouth dropped in shock. 

“Oh no. Oh fuck no.” He whispered, still loudly enough that you could hear him, falling to his knees with a look of horror painting his face. 

You felt like you should be offended but there was something about the look of pure despair and fear on his face that made you more concerned than annoyed. You’d always been worried your soulmate might be a jerk, but the magic which was responsible for it seemed inexplicably complex and the matches always seemed to work.

Sans looked at him sympathetically, much to your confusion. “I know bud. But ya gotta make the best of it. Sides things are gettin’ better in your verse aren’t they?”  
He gave Sans a deathly serious look. “Sure things is gettin’ better. But they ain’t that good! Can you imagine the uproar? I can’t have a human soulmate!” 

“I’m still here you know.” You interjected. He glanced at you distractedly, and wiped the fat drops of red sweat from the top of his skull. 

“Uh yeah, sorry doll. It ain’t nothin’ personal, promise. S’just, I’m not in the best situation for me ta be discoverin’ a soulmate an’ all. My universe don’t exactly have the best track record when it comes to humans.” He explained. 

“Sure. But you aren’t there now are you? But I’m guessing we’ve got to stick together for a bit till we figure out what happened. So can you at least be civil? Oh, and I need something to call you, can’t exactly call you both Sans.” 

“Ey now, I’ve made great strides in my civility lately. Just be glad ya didn’t meet me a year ago. You’d probably be dead where you stand.” As he spoke, he blinked, and his red iris disappeared leaving to empty black sockets. Then he blinked again and they were back. 

You shivered. You couldn’t help but feel like he meant that. You knew you should be more afraid of him than you were, and in truth that scared you too. You knew it was mostly probably due to the soulmate magic, but you couldn’t be sure. You swallowed dryly. 

He seemed to notice this and offered you a toothy grin. It was dangerously close to a leer. 

“As for names sweetheart, I’d go with callin’ me Red fer now. S’what we usually do.” 

“Uh…usually?” You inquired. 

“Right. Like when one of us visits another universe, or gets trapped in another cause some meddlin’ ass can’t keep his mitts off the science and endangers the whole multiverse.” He shot Sans a look. 

“Wait, visit the other universes? There’s a way for you to do that? And also, what do you mean endanger the multiverse?” You asked worriedly. 

“Uhm, well see there used to be a way fer us to travel between AU’s. One of us, can’t remember which discovered it. Made life fer Ink a hell of a lot easier, he didn’t have to taxi us all back every time one’ve us got stuck in another universe. But they were put out of use about 3 years ago since they was damagin’ the multiverse, and it could all collapse. Even Error didn’t want that ta happen, fuck knows why, that bastard loves destruction more than anyone I know, even Boss.” He complained. You felt a bit lost. You assumed these people were other versions of Sans, and he seemed to agree with most of what Red was saying. 

“Ink.” He offered as an explanation. 

“Yeah you could be right there.” Then Red seemed to notice your confused expression. “Right, me bein’ here. Well, basically, it means that your universe an’ mine must be really close together right now. If you think of ‘em like huge bubbles, they kinda float around and move. The closer two universes are to each other, the easier it is to make a bridge between ‘em, an’ I’m willin’ ta bet that’s what yer machine did. But the hole means there’s a part of my bubble in yours now, and so the two universes are linked together. Since  
I’m a major part’ve my verse it means mine can’t move until I’m back there, and so neither can yours. The longer I’m here, the closer the two verses become. Eventually they’ll smash into each other and obliterate each other.” 

“Okay. That makes sense. So is there a way for us to get you back to your universe Red? Can we use the machines you guys made?” You asked.  
Red opened his mouth to argue then closed it. He looked at Sans. 

“Y’know, that might work.”  
Sans shot Red a look that read are you mad? 

“I know; I know but hear me out Glasses. The fabric between the two universes is already weak from the first tear, rippin’ it again won’t be hard. The sooner we act, the less magic we need, an’ the faster I’m back, the less disturbance it’ll cause to the multiverse.”  
Sans seemed to think about it for a moment, searching for a reason to deny it, to protest. When he was met with none, the pros heavily outweighing the cons he sighed. 

“Alright. I think I’ve still got mine around here somewhere. Its gonna need some fixing up though, so you two will have to hang tight for a bit. Y/N, why don’t you and Red go see what data you can salvage from the machine inside?” 

You nodded. It would be a good distraction. “Come on Red. I’ll show you around.” The skeleton seemed willing enough to follow you, and you could’ve sworn you felt his gaze sweep appreciatively over your figure, but when you looked round he was looking directly ahead and merely cocked an eye…bone, when you looked at him in confusion. A snigger when you embarrassedly whipped your head back around roused your suspicions further. 

Once you and Red had collected all the results you were able to quickly dismiss them. They were unusable, the abnormal spikes in energy which seemed to have been caused by Red crossing over into your universe being anomalies you couldn’t use to confirm or dismiss your own theories on soulmate magic. 

So the two of you were left with time to talk. Which was why you were now both sat in the office, you in a recliner, and Red in a swivel chair. Red clearly felt the awkwardness as much as you did because he soon tried to break the ice. 

“Hey, why did the monster kid fall off the swing?” Ah, jokes. They were Sans’ speciality so you shouldn’t have been surprised. 

“I don’t know.” You smiled, waiting for a joke or pun of his usual calibre to follow.

“Cause he had no arms!” Your eyes widened at the punchline as Red began to howl with laughter. He had a nice laugh, deep and hearty. Then he paused. “Ah wait, shit, you humans are all sensitive bout those kinda jokes ain’t ya?” Both of your hands were clapped tight over your mouth and your eyes were wide in what must have looked like a state of horror to Red. 

Then to his surprise, you burst out laughing. He’d never yet met a human who’d laughed at one of his jokes. Sure Frisk had offered the odd chuckle, but it was obvious they either didn’t understand or were horrified but wanted to make him feel better. 

But you, you were laughing just as hard as Toriel had, the first time he’d made a knock knock joke to her through the door. He watched you double over in laughter, and couldn’t quite freeze out the curl of warmth that spread through him at the sound of genuine laughter, and from a human, his soulmate no less! 

Breathlessly you wiped away the tears from your eyes. “Ah, sorry. I know it’s the kind of joke I’m supposed to be horrified by, but black humour is my weakness.” You said, apologetically. 

Red’s eyes lit up and he smiled a wolfish smile, but still the most genuine smile you’d seen since he arrived. And anyway, any smile was going to be wolfish with those teeth. 

“What’s black and stuck ta the ceilin’?” You almost looked up to see before you realised it was another joke. 

“Uh, I don’t know.” 

“Not a very good electrician.” Your lip trembles, and suddenly you’re laughing again, sides burning with a lack of oxygen.  
This went on for about half an hour, before you finally looked up at a soft cough to see Sans standing in the doorway. 

“It’s ready to go.” He informed you and Red. You couldn’t help the wave of disappointment that fled over you, and as you looked you saw Red grimace.  
The two of you escorted Red to the machine. It was tall, about twice their size, made of metal and lined with blinking green lights.

“Welp, this is me. Hey doll, thanks fer givin’ me a great time this afternoon. Haven’t laughed like that fer a while. I wish ya could come with me, but that ain’t a good idea. Maybe one day though. An’ I gotta say, if I had to have a soulmate, I’m sure glad it was you.” He pressed his teeth to your cheek in a boney pseudo kiss. You caught his sleeve, causing him to turn and look back at you. Summoning all your courage, you leaned in and placed a kiss on his teeth. Both of you went crimson from embarrassment and awe. 

Sans cleared his throat noisily, and Red straightened up, as though he had been hit by a bolt of lightning. 

“Ah, right. Yeah, guess I’d best be goin’. See ya.” He gave you a quick hug, and walked quickly into the machine. The last thing you saw was Red’s blushing face as the doors closed. Then there was a bright flash and the doors opened to reveal an empty metal room.  
Sans sighed with relief. “Well at least that’s all over. You okay?” You tore your eyes from the inside off the metal plating, where they had been fixed after the pang of disappointment which ran fleetingly over you when you saw the empty chamber. 

Still, you smiled brightly at Sans. “Yeah. I just, never thought I’d like my soulmate so much. Or meet them at all for that matter.” You brushed yourself off, and removed the goggles which you realised had been perched on your nose this who time. You blushed. Could he really have thought you were attractive with those on? 

Shaking your head dreamily you turned to Sans. “I’m going to get a coffee. Do you want anything?” 

“Nah I’m good. You go on ahead.” Sans replied. You gave him a thumbs up, and set off for the cafeteria, whistling the tune of Once Upon a Dream. The coffee there sucked, but it was better than nothing at all.  
You couldn’t wait to see Red again. 

 

 

 

Sans waited until he was sure you had gone, then sighed. Rolling up his sleeve to look at the words marked in cursive on his arm.  
‘It’s a pleasure to meet you Dr Sans, my name is Y/N. Y/N L/N.’  
Guess you can’t win ‘em all eh?


	2. Drunken Distraction

**Summary for the Chapter:**

> The Reader has something to tell Sans. Unfortunately he's a little distracted.

**Notes for the Chapter:**

> Just a small update for now, with some clues as to how the plot might go, and for those who were worried about Sans!! Enjoy!

Sans, was drunk. Really drunk. 

It was a week since you’d met Red, and you’d gone home for the evening, after working hard in the lab all day. You were undeniably happy, and had invested time in learning about the multiverse. You had taken out several books on the subject, mostly by overrated scientists, theorising on a subject they couldn’t grasp, but you mainly spent your time asking Sans about it. It was a logical step; Sans was the one person with unfaultable knowledge on the subject you could turn to. You had both agreed you would have to be careful working with soulmate magic now that you knew it was part of the multiverse and not just your own universe. 

He was happy in some respects, he got to spend more time with you, which made his soul thrum with happiness. But, on the other hand he knew that you were only interested in it because of Red. Which stung. He’d known you had a soulmate of course, and he’d known it wasn’t him. And he thought he might be okay with that eventually, but now he knew he was your soulmate. It just wasn’t his version of himself. That, hurt more than not being your soulmate at all, the prospect that he was, but an alternate version of himself that you liked more. 

He’d never entertained the possibility of a soulmate. When he was younger he was excited to meet you, and spent time wondering what you’d be like. After all those years, he never thought he’d lose you. But as time wore on and he played Frisk’s game of deception, kill and reset it began to look less likely that he would ever meet you. He even resented you for a while. Where were you, all that time when he was dying over and over, distressed and alone, going crazy? That was before he’d met you of course. Of course. He couldn’t resent you when he met you. The moment he met you, he’d practically fallen over himself in as a cliché a manner as he could have.

Maybe that was why he hadn’t told you. Maybe it was because he knew what your mark said. 

He hadn’t been expecting it. You were just so…you. Nervous, but with a spitfire heart that told him you’d challenge any thoughtless statement. You were kind, funny. Sometimes you weren’t confident, and had your doubts. You’d had your share of misfortunes, but Sans was always there to listen to you. You were best friends, and the people you both trusted most. 

And yet, he couldn’t bring himself to tell you about his mark. He couldn’t bear to see the pity in your eyes, as you realised the truth, that he wasn’t a blank canvas at all, that you were his soulmate, but he wasn’t yours. That he was one of the rare cases, and yet that very rarity he despised. He wanted nothing more than to be like everyone else. To be happy and contented in his bliss with his soulmate. To dwell in uncorrupted ignorance. Being different was overrated. He never asked for this. Never asked to remember all the things he did, to be cursed in this way. But it seemed that the universe had cursed him to a life of tortured solitude. 

He wasn’t sure what he had done to deserve such punishment, yet it seemed to get a little better. That’s what you’d say anyway. You were always an unquenchable optimist. You’d say he’d made it to the surface. That there were no resets. He guessed that he’d gotten more than he was ever anticipating to get, that asking for you too would be like asking for the sun. Because that’s what you were to him. the brightest star he’d ever seen, and the only one he’d never be able to obtain. He couldn’t even blame anyone for this one. Even his alternate selves were luckier than him it seemed. 

And so, was it any surprise he was here, an hour later and 8 bottles of ketchup down? Life once more seemed like it might be a joke on him. that his dreams eluded him. He sat in the swivel chair, black fabric and sponge cushioning his bones. It was over wasn’t it? He’d lost, you’d chosen Red, you’d loved him, and you were gone. So why was it he couldn’t move on? Who was he now without you? Petty and dull with the nerve to doubt you and your decision?

He reclined, feet on the counter, blue faced from the condiment, and the world seemed to spin despite the him being perfectly stationary in the chair. It often felt like this, like the world was moving without him and he was left, dizzy and confused. It was just most of the time it wasn’t caused by being intoxicated. There was probably some deep philosophical reason for his suffering, and a lesson he could take from it, such as he should love himself before loving another, but honestly he didn’t care. He just wanted you. and it hurt that he couldn’t have you. 

He sighed and rested his skull on the cool countertop. It was only when the door slammed open he jolted upright, drool hanging from the corner of his mouth.

You hadn’t been expecting Sans to be drunk. But when you entered the lab, full of exuberance, confusion and a little fear, your mind buzzing with questions. However, they all vanished in a second when you slammed the door open and saw Sans. 

“SANS! Listen I’ve got to tell you something….” You trailed off as you noticed his face.

His face was blue under his sockets, right across where his cheeks would be. Dark freckles were speckled haphazardly across his cheekbones. His sockets were wide and the lights inside were dilated to larger than usual, from what you didn’t know exactly, although he was showing signs of intoxication. 

His regular clothes had been abandoned in favour of a massive blue jumper which was thinner than his usual hoodie, still hanging from his bones but better fitting, and revealed Sans’ small frame. His shorts had been ditched for a pair of jogging bottoms which ended around his ankles. It was obvious these were clothes which were tailor made for him, with padding but more closely fitted, most likely due to Toriel. His glasses were perched wonkily on his face, the tape which held them in place having come loose, and been reattached sloppily by Sans. One side was higher than the other, and from one side of his mouth there was some blue tinted saliva. The sight was adorable as Sans sleepily rubbed one of his sockets sleepily. You felt a twinge in your heart you had only felt around Red. 

“Y/N? W-what’re you doin’ here?” He slurred. Yep definitely drunk. 

“I had something to tell you, but that doesn’t matter right now. Are you drunk?” You noticed several empty ketchup bottles on the counter. Could he really have gotten drunken off ketchup??

“Nah ‘m not drunk. Juuuust a bit tipsy s’all.” He yawned. “an’ tired.” You shook your head at him fondly. 

“Come on Sans, you can’t sleep here.” You put an arm out and tugged him to his feet. He was surprisingly light. His usual pink slippers had been replaced by huge blue sneakers, similar in appearance to Red’s shoes. 

You looped your arm around his waist, and he laid his on your shoulders, using you to keep himself upright. 

“Where’re we goin’?” He asked dozily. 

“Well I don’t know where you live, and it’s too late for you to call Papyrus, so you’ll have to come to my apartment. You can sleep there. “  
His eyes widened as you spoke, and under his breath he muttered “Wow.”

The two of you made your way through the dark streets together, Sans wobbling precariously, causing you to tighten your grip on his side. You could feel his slender bones through the jumper, blue as the night’s sky. 

When you finally reached your apartment it seemed like it had taken an eternity. You couldn’t help but be glad Sans wasn’t a drunk singer, although he was incredibly sleepy and adorable. Mumbling random science facts under your breath he smelt like salt, mint and oil. It was an odd combination, but somehow soothing.

You fished into your pocket for the keys and one handily unlocked the door, nudging it open with your foot. 

You escorted Sans into your bedroom. It wasn’t big by any means. You simply didn’t have the money to spend on it, and to be honest you didn’t care that much. It was big enough for your needs. 

You pushed him gently towards the bed, where he collapsed fairly quickly. You threw the covers over him and smiled. It seemed he was already conked out. You removed his glasses and pressed a kiss to the top of your head. 

“Night Sansy.” You turned for the door, to go and settle on the sofa.   
Something caught your arm and you looked back to see Sans sat up sleepily. His eyes were focused though. 

“Stay with me? Please. I-I don’t want to be alone.” He whispered, faint blue tears lining his sockets in fear.

You studied his face for a moment and then nodded. 

He sighed in relief, scooting over for you. “Thank you.” 

You awkwardly lay on the bed, unsure how to approach the situation. 

Sans snorted. “Not like that. C’mere.” He grabbed your shoulder and pulled you into him, so that his head was resting on your shoulder, his arms looping around you to rest on your stomach, his chin resting on your head. 

You lay there, stiffly, listening to Sans breathing until you relaxed. 

You sighed, and gently, so as not to wake the sleeping skeleton, rolled up your sleeve to look at the new mark which now circled your arm. 

You wanted to ask him about it, but it could wait for now. It could wait until the morning. For now, you were content just being together.

**Notes for the Chapter:**

> Tah dahh! Hope you liked it! This was only a small teaser! Please let me know, and either request another Sans to make an appearance or tell me your plot ideas! You guys are awesome!!!


	3. Love me, love me, say that you love me.

**Summary for the Chapter:**

> The morning after the impromptu sleepover with Sans. Just how awkward will this be?

**Notes for the Chapter:**

> Hey guys, I hope you enjoy this chapter! I need a few more Sans' to make appearances so if you want to see one, leave it in the comments! If you have a plot idea let me know either here or at https://www.tumblr.com/blog/alex-thinks-about-life! Asks and submissions are open, so even if you don't have a tumblr account you can still send an ask, and if you're interested in being a beta reader for any of my work, let me know! You're awesome!

When you opened your eyes the next morning, you were not expecting to be looking into a pair of huge blue eyes, only a couple of centimetres from your own.  
“…AHHH!” 

You jolted your head backwards into something firm and warm. Glancing up, you saw Sans, sans glasses, arms wrapped around you protectively. Apparently this new figure didn’t warrant the same level of danger as Red, since Sans’ eyes weren’t alight with magic. But then, you supposed the individual wasn’t attacking in the way Red had. You could still sense the magic in the room though, Sans’ own magic with its comforting familiarity and a different magic. This magic was cool, refreshing. If you could describe it with a taste it would be minty fresh and sharp. Whilst it was similar to Sans’ in some aspects it was further from his own that Red’s had been. You wondered whether this was indicative of the individual’s personality. You couldn’t really see him anymore, as Sans had clutched you close to his chest, blue fabric obscuring your view and almost suffocating you. 

“Sans…” You pushed him back a bit so you could breathe, sitting up so you could see the intruder to your domestic peace. He sighed in resignation and released you, though he kept a hand on your shoulder. You were so distracted by the newcomer that you forgot to question Sans on why he didn’t have a hangover. Maybe magic skeletons just didn’t get them, or maybe it was because it was the result of a ketchup binge. The individual was stood on the opposite side of the room, perched on top of your dresser. If he wasn’t a skeleton, you were sure it would have buckled under his weight. He was…dressed eerily similarly to Papyrus on the few occasions you had met him. He was around the same height as you, although he appeared to be closer to Sans’ height. 

His arms were covered up to the elbow with a pair of blue gloves. He was wearing a large white t-shirt, similar to Sans’ own usual one, as you could see the sleeves hanging out from under some kind of dark grey armour, only it wasn’t made of metal but some kind of dull grey material. The sleeves reached his mid humerus. The armour seemed to be composed of two parts, each section lined with a bright blue at the edges. The main section was the part which sat over his torso, and then there were two plates, each of which seemed to clip over the tops of his shoulders. 

Over the top of the armour and covering his neck was a bandana of the same blue as his gloves. It looked slightly worn as though it was worn every day, the knot extending into two points of fabric like a bow next to the side of his head. At the back it seemed to hang down longer like a mini cape. He wore baggy black trousers which were tucked into a pair of stylish blue boots. 

His hands were clasped together and he had an expression of worry on his face, which was strikingly similar to Sans’. He had a pair of large blue lights in his sockets, a feature you had never seen in either Sans or Red, or even Papyrus or Dr Gaster. Dr Gaster, Sans and Red all had white lights for eyes, with the exception of when they were using magic, although Red preferred his one red light to the two white ones, and Papyrus rarely had any lights at all. The skeletons eyes seemed to switch between you and Sans, although it was the latter he addressed his question to.

“Is the human okay Classic? I didn’t break them did I? I truly did not mean to! I just wanted to introduce myself!” He looked about ready to cry. 

Sans snorted a little. “Nah, don’t worry about it Blue. It’d take a lot more than you first thing in the mornin’ to break Y/N.” 

They…Blue, exhaled seemingly in relief before turning his bright eyes to you. “Hello human! I am the magnificent Sans, although you may call me Blue! And may I just say, you are very pretty!” A bright blue blush tainted his cheeks as he spoke, and you felt your own face grow hot at the genuine compliment. Sans’ hand seemed to tighten on your shoulder. 

“Um, thank you Blue! I’m Y/N! It’s a pleasure to meet you!!” You couldn’t help but feel like you had heard this introduction before…but where? It was only in that moment that your forearm began to tingle, and as you watched Blue’s sockets widened and then dissolved into pools of joy. His smile grew until it looked as though it must be hurting his cheeks. You rolled up your left sleeve, to see the new words there, shimmering a light blue. 

“Woah. Thought you only had one soulmark?” Sans asked, looking over your shoulder, his arm stretching over, phalanges gripping your wrist as he turned your arm to see the marks better. 

“I did! That’s what I came to tell you yesterday. This one just…appeared!” You explained, gesturing wildly. 

“So…the human and I are soulmates?” Blue asked, excitedly clapping his hands. 

“Well, sure looks that way. What are you doin’ here Blue? How’d you even get here? Can’t see Orange sendin’ you on your own.” Sans asked of his double. 

He shook his head. “Papy didn’t send me! I was patrolling the woods in Snowdin when there was this really pretty tear, like we used to get in the old machines. I went over to investigate, and something pushed me through! The next thing I know, I’m in this room with you and Y/N!” He explained animatedly. 

Sans seemed unsettled. “That’s not good news. It was one thing when Red came here, but this rip was unprovoked.” 

“Wait, Red has been here too? How?” Blue asked. 

“Same way as you I guess. Rip. But we sorta provoked his arrival.” Sans admitted sheepishly. Blue folded his arms over his chest. 

“Classic, what did you do? You know you have to be careful about these things! Especially if they involve my soulmate!” Blue scolded.

“Yeah yeah I know. Sorry Blue. Anyway, we managed to get Red back to his verse, without a hitch it seemed. But you bein’ here suggests otherwise doesn’t it?” He asked. Blue looked thoughtful. 

“I suppose it does Classic. Unless, it is fate that I, the magnificent Sans have appeared here to meet my soulmate!” He proclaimed.  
Sans didn’t look impressed. He merely offered a “Hmm” in response.

“Uh…Blue?” You asked, wanting to voice your concerns. The skeleton turned towards you with a blinding smile. 

“Yes, soulmate Y/N??” 

“Why do you call Sans Classic?” His face creased for a moment into a frown. 

“We call him that because this is what we Sans’ consider the Alpha universe. It existed before all of our own AU’s which means this universe’s Sans existed before all of us. It is easier to consider it like a plant. In which this universe is the stem and our universes are the leaves which come off of it. if they are removed, the plant suffers but it does not die. However, if this timeline is removed, none of ours can exist without it.” He explained, the analogy being very helpful, and also showing you despite his childlike demeanour Blue had a complex understanding of the situation. Well, he was an alternate version of Sans so it made sense. 

“Okay…” You began hesitantly.” So what do we do now? Can’t we get Blue back to his dimension the same way we did Red?” You asked Sans. 

“No. It’s too risky. In fact, it may have been us doin’ that which caused the rip which Blue came through. Even if we could, its Sunday. The labs all locked up. We’ve gotta wait until Monday when we can get back into the lab and maybe see if we can find an alternative way of gettin’ him back.” You listened to Sans and began running a few ideas through you mind, basing them on the same technology you had been using to create the old machine for evaluating soulmate magic. 

Apparently at some point during your internal deliberation Blue became bored, having a shorter attention span than Sans and Red, as he began humming a small tune to himself and adjusting his scarf in the mirror. You wondered if that was a frequent trait in Sans’.

“Let us not waste a moment of this bonding time then!” Blue shouted, jumping from your dresser to the floor.  
You and Sans looked at each other. 

“He’s got a point. We can’t do anything today. We might as well spend some time planning what to do tomorrow.” You admitted. Sans reluctantly nodded his agreement.

“Well both of you need to leave the room so I can change. I’m still in my clothes from yesterday. Oh, actually you are too aren’t you Sans? Hang on, I think I’ve got some old clothes you can borrow.”

“Uh, nah, don’t worry about it kid, I’m fine honestly.” Sans protested, blushing furiously at the idea of wearing your clothes. 

You shook your head assertively. “Nonsense! You can’t wear the same clothes as yesterday! Give me a moment and I’ll find something! Now, out!!” You threw the two skeletons from your room, and shut the door, turning to your room to find clothes for the day ahead. 

 

Sans blinked as your door shut in his face. It took a moment to register and then realise his glasses were still in your bedroom. He decided he would retrieve them later. For now, he turned his attention to the rest of your apartment. It was smaller than his own house which he shared with Papyrus, despite the fact you both worked the same job, but monsters were notoriously wealthy, the gold they used as currency underground being massively valuable on the surface. Many had tried to exploit the monsters because of it, but luckily most were sharp enough to pick up on it. After a few years of campaigning the monsters were eventually granted the same rights as humans, which was a huge step in the right direction.

Your apartment consisted of one bedroom, a bathroom, and a living room/kitchen. It was mostly tidy, with piles of papers or books stacked neatly in the corners. A plush blue sofa faced a TV with a few consoles underneath. Sans strongly suspected you might be able afford a bigger apartment, but you simply didn’t need one. 

Blue had made a beeline for your kitchen, and Sans was about to follow him, when you emerged from your room. The two of you made eye contact. For Sans, time seemed to slow just a little. How was it fair, that after being awoken at a horrible hour by an intruder into your house, and given 10 minutes to get dressed, you could look so cute?

“There’s uh…clothes on the bed for you. Sorry they aren’t the best…” You said apologetically. 

“N-no that’s okay, I’m sure they’ll be fine. Uh…thanks again.” He replied, blushing blue lightly and slipping past you into the bedroom. 

On the bed was laid a big black jumper, a pair of navy sweat pants, which he was thankful for, as any form of jeans would not stay on his bones, and a pair of boxers patterned with bones. He chuckled at your good taste, but soon dissolved into a blue mess as he slipped the boxers over his bones. The sweatpants evoked much the same response. He then pulled the jumper over his head. It was a little baggy, but that was something Sans appreciated in clothing, the sleeves only hanging a little below the tips of his phalanges.  
On the jumper was the word ‘cutie’ and underneath the symbol for pi. 

Deciding not to linger in your bedroom for longer than was necessary, Sans grabbed his glasses from the side, applied the tape to the sides of his skull and exited the bedroom hurriedly. 

In the living room he found you and Blue, sat on the sofa together, facing the TV. It looked like you were booting up some kind of video game, and from the looks of the microphone in your hand, it was some form of karaoke. 

As he watched, you scrolled down the selection of songs, until Blue tugged on your arm, excitedly indicating one of them. You chuckled and pressed a button on the controller in your hand, laying it on the sofa next to you as the music began to play. 

It wasn’t a song Sans recognised. But then he wasn’t a huge modern music fan. He hadn’t had access to much in music in the underground, and despite your best attempts, you had yet to find a genre he liked. 

Blue leapt from the sofa as the music to ‘Lovefool’ began, pulling you up with him, laughing. The two of you shared the microphone, heads close together. 

“Love me love me  
Say that you love me  
Fool me fool me  
Go on and fool me  
Love me love me  
Pretend that you love me  
Leave me leave me  
Just say that you need me  
Love me love me  
Say that you love me  
Leave me leave me  
Just say that you need me.”

Blue sang his lyrics at you, twirling and posing adorably as he did so. He had an undeniably good voice, although both Blue and Sans were enraptured by yours. You felt your heart melt a little, and when the song finished, you pressed a soft kiss to the top of his skull and murmured “Love you”. The effect was enough to cause the small skeleton to go bright blue. 

“G-gosh! Y-Y/N, I-“ He broke off when he saw Sans standing in the doorway, doing his best to hide his hurt. Would it really be so much to ask for you to love him, to need him, to want him?

You looked to see what Blue was gazing at, and saw Sans standing there. You unconsciously broke into a grin as you let out a wolf whistle, you and Blue sitting back down on the sofa. 

“Looking good Sans!! Look, Blue and I made snacks! Why don’t we all watch a movie together??”  
Sans couldn’t help but smile back at you. Your smile was just so bright and genuine, it was infectious. 

He flopped down on the other side of you. “Sounds good buddy. What’re we watchin’?”  
“WALL-E!” Blue exclaimed. “Y/N says it’s really good!” 

“Oh yeah?” You passed him the DVD case. He briefly appraised it with his eyes before nodding in approval. “Nice choice bucko.” He leant over your lap and grabbed a handful of nachos, crunching them down throughout the movie. 

It was fairly uneventful, Blue watching the film attentively, and shushing any commentary that might otherwise have gone on. 

Slowly, you subconsciously began to lean towards Sans, until your head was resting on his shoulder, and one arm was slung around your shoulders. It was these moments Sans lived for. He could live with not being your soulmate as long as he got to be your friend. As long as he got to be around you, to be close enough to you to feel the heat you emitted, the softness of your skin, the small huffs as you exhaled, the sweet mint of your toothpaste on your breath. He could live with that.

When the movie reached its climax, and it seemed as though the small bot had been crushed Blue turned to you with fat blue tears in his sockets and buried himself in your arms, small sobs occasionally erupting from him. 

“Shhh…it’s okay Blue look!!” you consoled the skeleton, as Wall-e reappeared, perfectly fine on screen. Blue let out a cheer and bounced once on the sofa, as the credits began to roll up the screen.

Just then, in true dramatic style, a giant rip appeared in your living room, and a skeleton stuck its head and shoulders through. The skeleton looked like Papyrus, seemingly close to him in facial structure, but the cigarette in his teeth and the orange hoodie were not featured on the Papyrus you knew, in either battle body or ‘hangout’ clothes.  
Blue it seemed, did recognise the skeleton, as he bounded towards the rip. “Papy!!” The skeleton looked briefly relieved as he spotted Blue. 

“Sup bro. I came to join the party. Hope it wasn’t too…tearible.” Blue looked scandalised at the pun.

“PAPY! You’ve only been here ten seconds! What an impression you are making! And, are you smoking again? You see what happens when I leave you on your own? What would you do without such a cool guy to take care of you?”

Sans snorted. “Well, I thought it was pretty punny. How you been keepin’ Orange?” He asked of the taller skeleton. 

His eyes flickered to Sans. “Oh hey ‘ridge. Yeah not too bad. Lucky ‘nough to find one of these rips in the woods.” He turned his attention to Blue. “Ready to go?” 

Blue nodded enthusiastically. “Yes brother! Just wait until I tell you about my adventures!” 

Orange’s eyes swept to you. “Yeah, you can tell me about it when we get back bro. See ya, ‘ridge, Y/N.” And with that he disappeared back through the rip. 

Blue turned his attention to you. “Farewell, lovely Y/N! May we meet again soon!” He pressed his teeth to your hand, gave you a quick hug, and he was gone. 

You sat there in shell-shocked silence for a moment. “How did he…?”

“Eh, with Orange you probably shouldn’t ask.” Sans informed you. You blinked, shook your head and began to clear away the dishes. 

Sans had decided to tell you. Regardless of whether you felt the same, he couldn’t keep it a secret any longer. He paced over to the kitchen door where you were washing up the dishes, nervously tapping the door frame. 

“Y/N, listen, I’ve gotta tell you somethin’. Look, I know I’m not yours, and that's fine, that isn't what this is about, but, you’re my soulmate. And, I’m not the best with words I know, but I tried to make it obvious, and you never noticed the way we just belong together. So I thought I’d just come out and say it. I love you, Y/N, and even if it can’t ever be, I just hope we can be friends, because just bein’ around you is enough for me. I'm just askin' that you don't send me away, please.” Tears pricked behind his sockets as he waited in agony for your response, drops of sweat trickling down his skull. He never imagined confessing would be so hard, that he wouldn't know what the other person might see.

You turned to face him and opened your mouth to speak. 

“What? Sorry I couldn’t hear you.” You said, removing the white earphone. 

“Oh, uh it was nothin’ important don’t worry. Hey, I’m gonna head home now. Thanks for everythin’ though, especially last night and helpin' me. See ya bud.”

“Okay. See you tomorrow Sans!! And don't mention it, what else are friends for?” You waved. 

“Yeah. Friends. See ya.” 

Love me, love me.

Say that you love me. 

Please.

**Notes for the Chapter:**

> Oh....poor Sans!! .-. He will get a happy ending I promise!!! I don't know if it's obvious I give each Sans a different way of speaking! Props to all you guys who spotted the SU reference last chapter!! Let me know if you enjoy this fic and want to see more! Remember to comment with a Sans you want to see! Stay awesome, Trash Queen signing off!


	4. Love, Lust and Lords

**Summary for the Chapter:**

> Many thanks to the lovely imagication for their suggestion of this chapter! Introducing Underlust Sans and SwapFell Sans!! Why am I even still writing this jeez, I can't write for pie.

**Notes for the Chapter:**

> Hello everybody! This was actually an oddly tricky chapter to write, since I had to work in some plot, and work with characters I don't usually!! Still, I hope you enjoy it!! Underlust of course, belongs to the lovely @nsfwshamecave on tumblr, and I apologise to her for my terrible representation of her Sans. This is, of course not canon and nothing to do with the plot for Underlust!

You were beginning to appreciate how books must feel. It had been a week since Blue had appeared in your apartment. You hadn’t noticed it until you were having your shower, a third soulmark curving over your thigh, and a fourth above your hip bone. Every mark was different, a different colour, as different style. Red’s was sharp, and angular. Blue’s was soft, bubbly and curvy. You were pretty sure if they kept appearing you were going to run out of skin. 

Why exactly this was happening you weren’t sure. You hurried to your computer to check your files. Scrolling down the screen, it was as you suspected. Whilst the nature of soulmarks was still primarily a mystery, there was some information about them. 

For example, it was recorded that some blank canvases could later obtain soulmarks, usually to their shock. It was a rare occurrence, rarer than being a blank canvas in itself. But you couldn’t find anything about someone with an existing soulmark gaining another, let alone 3 more. You could only pin it to the experiment you and Sans had conducted, hoping something from that magic was the magic from the machine gone haywire. You liked your soulmates so far. Red and Blue had been very unique individuals, and you felt your heart turn pleasantly when you were around them. But, something was off. You didn’t have the same relaxed feeling you did with Sans. Around them you were nervous and on edge, whilst Sans was so easy to get along with. His company was like a hot bath, warm and relaxing. 

Speaking of Sans, you hadn’t seen him much since the incident with Blue, where he had left rather abruptly. Any time you had seen him, he’d been acting rather awkwardly. You were worried you had messed up somehow. Like maybe you’d offended him. You hadn’t slept well since his sudden exit from your life either, and it was beginning to take its toll on you.

You made a mental note to ask him if anything was up. After all, you had the right to know didn’t you? To try and make amends. 

Besides you needed him, in case another version of himself showed up. 

As you heard the familiar sound of a rip, you groaned. You had inevitably jinxed it. It had barely been a week since the last incident. You had no clue about the nature of many of the alternate universes but Sans had warned you many of them were dangerous. But then, Red had claimed his universe was dangerous, which you supposed by all accounts should make him a dangerous individual. Yet when you looked at him, danger was the last thing you saw. You saw unease, fear and loneliness. It was as though the loneliness in him called to something in you, made you want to be there for him. and as for Blue, he was so sweet, you couldn’t comprehend him ever being dangerous. 

So it was not with fear you approached the bedroom where you had heard the ever familiar sound, followed by the confliction of puzzled voices.

“You? Oh Asgore help me, haven’t I seen enough of you to last me one reset?”

“Hey now, be friendly buddy!”

“Get your hands off me, you insufferable fool.”

“Oh, am I getting too handsy for you? You could always use that crop to stop me. Or would that just be encouragement?” 

“Why you little- “

The latter voice was cut off by your entrance into the room. Two. Two Sans’. Well this was new. 

One of them was lying down on the bed, and the other was straddling him. 

The one on the bottom, reminded you of a cross between Blue and Red. Red boots were on his feet, with heels that would have made him a little taller than you, the tops of which were level with his knees and thigh high socks, with black shorts and a belt, covered with small golden spikes and a golden skull belt buckle. The tops of his hips protruded over the low belt, and the tops of his thighs were left exposed. His spine was uncovered, until just below his ribs, where a set of armour, similar to Blue’s was worn, except for the difference in length, and the grey way switched for black and the edges lined with gold. Both the shorts and armour were lined with a light blue. A red bandanna like Blue’s sat around his throat, although his was far more distressed looking. He wore red elbow length gloves, with some grey material protruding from under them up until the middle of his humerus. He had two bright blue lights in his eyes, a scar running through one of them. He wore a smirk which reminded you a lot of Red, and his hand was clutching a riding crop. 

The second was wearing a pair of blue boots, with leather or latex trousers, leaving you with a clear view of his hip bones and spine. He wore a black crop top, with a light blue heart on the middle of the chest, and a longer purple jacket. It was sleeveless, with blue fur lining the bottom and collar of it. The fur around the collar was far fluffier and unrulier. His hands were covered by black fingerless gloves. A light purple was hinted at around his cheeks, and his eyes were two bright white lights, like Sans’ and not the alternate versions you had seen. 

Both looked towards the door when you entered. The lower Sans looked mortified, whilst the top looked curious.

It was the latter who spoke first. 

“Oh hey, it’s a human. A pretty hot human too.” What? You made eye contact with the Sans who merely winked at you. 

“Of course it’s a human, you nitwit. Although I must say I’m not surprised you don’t know what one looks like.” 

“What’s that supposed to mean buddy?” The other asked, face calm, but tone dangerous. Any other Sans might have seen it and backed off, but apparently this one was looking to get his butt kicked. 

“It means, you infernal half-wit that you- “ 

“Excuse me? I know you’re both Sans’ but…who are you?” You asked. Simultaneously, their eyes widened and they shared a look. 

“Oh, you have got to be kidding me.” The bottom Sans growled. “Soulmates with a human??”

“Woah, Cherry, chill. You’ve got to admit, it isn’t hopeless, having a hot soulmate.” Whilst the Sans was being very complimentary, you couldn’t help but feel that there was something about the way he spoke that made you shiver. He dismounted him companion, who immediately sat up, scowling. He walked towards you, and you began to back up, slightly uncomfortable with the invasion of your personal space, though not necessarily objecting to it. Something hard hit your back, and you realised it was the wall. The Sans placed his hand on the wall next to your head, effectively trapping you there. A light heat began to burn in your cheeks.

“Besides, having a soulmate can’t all be bad. They’ve got to have some…” His eyes flickered down your body “interesting kinks…” You could smell his breath, something sweet, as a purple tongue lolled lewdly from his mouth. Oh my. This skeleton had fangs. Actually, if you thought about it so did the other. Was that a common feature in Sans’? If it wasn’t, you couldn’t deny it was hot. The other Sans on the bed leaned forwards as if in interest, resting his hands on the top of his riding crop. 

“S-sans?” You squeaked, blushing harder as he leaned towards you.

You heard a door open and shut and a voice called out “Y/N? Are you in??” 

You opened your mouth to respond, when the door to your bedroom opened and in stepped no other than Sans. Dressed in his regular clothes you recognised a pile of clothes as your own in his hands. 

“I came to bring your clothes back. Listen I wanted to apologise for the way I’ve been actin’ the last few d-days...” His eyes seemed to grow as he took in the situation. 

You were pinned against a wall by another version of himself, whilst a third sat watching, smugly on the bed. 

And then suddenly the version keeping you against the wall, he was gone. 

Sans’ eye was blazing with magic and the Sans’ soul was glowing blue as he was slammed into a Sans pile on the bed, taking down the other Sans like a bowling ball. 

“Keep. Your. Hands. To. Yourself.” He growled, placing himself between you and the Sans’. He should have known something like this would happen if he stopped talking to you. It had been one of the most painful weeks of his life. He had thought some distance might give him time to cope with the events. He couldn’t have predicted how painful being away from you would be. It was made worse all the time by the thought you must now resent him. he’d acted so strangely; he wouldn’t blame you if you decided to cut off all contact with him. 

And now, when he’d finally lost the pride to keep himself away from you, to come crawling back on his knees and beg you to be friends with him again, he finds you alone in a bedroom with two of the biggest sleaze balls he knows!

“Sans! I missed you!” You cried in surprise and relief. Not only did it seem he wasn’t mad at you, he’d also come to apologise. You tackled him in a hug from behind, sweeping the small skeleton off his feet.

“Woah, kid! I missed you too!” He exclaimed, soul humming with excitement. You’d missed him. His lengthy departure from your life had actually had an impact. 

“Well why did you leave then you egg covered muffin top?” You scolded. “Do you have any idea how worried I’ve been that I did something wrong? That I messed up?”

“What? No, bud, it was me. I messed up. I needed some time alone, and I didn’t tell you in the right way. And I’m sorry about that.” 

You sighed in relief. “It’s okay, I’m just, just glad it wasn’t anything I said is all.” 

“Nah. You’re good. These two, on the other hand are not. They are very bad news. Cherry, Purple, what are you doin’ here?” You peered around the side of Sans, who still had one hand extended towards the pile of bones. Cherry looked annoyed, and Purpled looked amused, as the two tried to disentangle themselves. Cherry managed to free himself, and gave the precariously balanced Purple a hard push onto the floor. 

“I was out patrolling, and got sucked into one of those interdimensional tears. Unfortunately to keep being a part of the royal guard one has to perform a mandatory set of hours. I had Papyrus make dinner for when I return, so if we could get back in time for that, that would be good.” Cherry said disgruntled, dusting himself off. 

“As for me, I was on my way to Grillby’s. But I think it’s obvious why I’m here.” Purple boasted. 

“It, uh is?” You asked. Sans looked just as confused, so at least you weren’t alone. 

“Oh yeah! You guys are researching soulmate magic right? And that’s great, but you don’t have any clue what you’re doing!”

“And you do?” Cherry asked critically. 

“Sure I do pipsqueak. Look, in my universe, we’re all about love, lust, sex and relationships. So of course we have a stronger understanding of soulmates than you.”

Sans looked at him. “I hate to admit it but he could be right.”

“Of course I am ‘ridge.” He said, smugly. 

He sighed. “Right. well if we have to have this discussion, we are NOT havin’ it in Y/N’s bedroom. In the lounge you two. NOW.” He commanded, pointing to the door. A shiver ran through you at his voice. You had never thought Sans would be so dominant. Cherry exited the room first, followed by Purple, but not before he caught your eye, giving you a knowing smirk. 

Sans made sure you walked behind him in case either tried anything inappropriate, and the four of you filed into the lounge. Cherry took the armchair, leaving you, Sans and Purple to share the sofa. Unfortunately, it wasn’t a very big sofa. 

Sans moved to let you sit between him and the arm of the sofa, but was stopped by a hand on his shoulder. 

“Hold on just a moment there ‘ridge. I want to sit next to Y/N too. So how about we clear a space in the middle for them? After all…” his voice went eerily deep and his left eye flashed with purple magic, the right socket void of all light. “We are soulmates.” 

You didn’t know what it was, but something about the way Purple spoke then, caused Sans to growl and lunge towards him. 

 

He was going to kill him. How dare he? How DARE HE? Coming into your life, like he knew everything about you? Like the soulmark made it acceptable to put his hands all over you? Taunting him with something he could never have. 

Was he jealous? You’d better believe it. 

He was snapped from his thoughts by you settling between the two skeletons, and extending a red box towards him. 

“Pocky?” You offered lightly, hoping to ease the tension. Cherry already had one, chewing it thoughtfully with his fangs. 

“Uh…no thanks bucko.” He refused politely. You turned and made the same offer to Purple, who seemed to consider it.

“Thanks, but I think I’ll pass. No treat could be as sweet as you anyway.” He said, lifting a hand to tilt your face slightly. Oh my. You felt your blood racing to your cheeks, and you were struck with an unpleasable urge to lean forwards and kiss him. You were interrupted by a loud cough of laughter from Cherry. 

“Good God, Purple. I knew you were uncivilised, but I never imagined you could be such a cretin. Keep your hands to yourself for a moment and tell them what they need to know about soulmates.” He demanded. It looked as though a light red painted his cheeks, and Purple held up his hands in surrender, and reclined back into the sofa. 

“Whatever you say Master Cherry.” He winked at Cherry, who looked horrified. 

“Don’t call me that, you half-form lowlife!”

“Why not? I thought you liked it, my Lord.” Purple said in a teasing tone.

“Just tell them what they need to know, so I can kill you, you heathen!!” He yelped.

Purple snickered and you grabbed a stick of pocky, placing it in your mouth to distract yourself. 

“Right. Soulmarks. Well, essentially you’re soulmates with so many Sans’ because you probably have an alpha soul bond with one of the strongest beta universe Sans’. Imagine it like mitosis. There was one universe which split into two and then that universe split into two and so on. So naturally, the soulmate magic from the first divisions is stronger than say…the 50th universe. Now, your alpha soul bond is your main soulmate. They’re the one you’re actually supposed to be with, and their soulmark will usually appear around the chest or heart area, because the closer to the heart the mark is, the stronger the bond is, at least for humans, and more…lustful bonds appear closer to the genitals.” 

He placed his hand on your thigh, only removing it after Sans shot him a death glare. And still a smirk played on his face. “And if the Sans you’re soul bonded to, had a universe which created more universes, all those subsequent universes would also have that soul bond, although it wouldn’t be as strong, because they aren’t real exactly, they’re more like…shadows of your actual bond. “

“So, I’m not actually soul bonded to all of you?” 

“No, it’s likely you only have a bond with one Sans, from one of the more major universes. Once you find them, it’s likely all the shadow bonds will disappear from your body and theirs. So…better make the most of it.” With that, he leant forwards and grabbed the last of your pocky with his teeth, so that his teeth brushed your lips. 

Within seconds, a hand was on Purple’s shoulder, which you came to realise belonged to Cherry, as he tore Purple away from you, and you turned to Sans, burying your scarlet face in his chest. 

“You absolute idiot! Just what do you think you’re playing at? Do you have no common courtesy?!” Cherry reprimanded Purple who sniggered the whole time. 

“You two are leavin’. Now.” Sans growled, prying you off him and dragging the other two into the bedroom, much to Cherry’s horror and Purple’s delight. Their voices were muffled by the walls, but you felt it when they left, the heavy tingling which had been settled in your stomach throughout the episode disappearing. 

 

Purple and Cherry were stood by the rip Sans had managed to re-open, using the device he had spent his week away from you making. He’d had to do something to occupy his mind, to distract him from the longing in his soul.

“Hey Purple?” He called, as the two headed towards the rip, somewhat reluctantly, but knowing better than to try and fight Classic. His magic was stronger than theirs. 

“Yeah ‘ridge?” He replied.

“Don’t come back. That human is MINE. Spread the word.” 

“Exc- “They began to protest, but Sans swiftly closed the rip. The room fell silent and he let out a sigh he had been holding in all day.

 

He returned to the living room, where you were lying face down on the sofa, groaning lightly. 

He snorted upon the view. “You okay kid?”

“Mm…I’m just…glad it’s all over. My back is killing me.” You winced at the tension in your muscles. 

“Here. Let me give you a hand then.” You opened your mouth to ask what he meant, when you felt his hands, sliding over your back, easing out the tension as he massaged your aching muscles. 

“Oh Sans…you have magic hands…” You moaned. 

Sans blushed tinted blue. “Y-yeah I guess I do.” He continued and the two of you sat in contented quiet for a while. 

“Sans?”

The small skeleton jumped a bit, and nervously adjusted his glasses. “Y-yeah kiddo?” 

“Please don’t leave me like that again. I don’t think I could cope with losing you.” 

Sans flushed deeper blue, glad your face was buried in the sofa. “Sure. I won’t.”

“Promise?” Sans hated promises. 

“I promise.” 

“Thank you.” You mumbled sleepily, before crashing into the warm blackness, contented and safe in Sans’ presence once again.  
Sans stared at you for a moment as you slept. It was good to be back in your company again. It made him appreciate ow much he had missed you. He stroked your hair affectionately as you breathed in and out deeply before scooping you up. He couldn’t leave you to sleep on the sofa. He set you down in your bed, covering you lightly with the duvet. 

Then, placing a bony kiss to the top of your head he took his leave. 

 

Goodbye Y/N. I love you.

**Notes for the Chapter:**

> So that's an update!! Let me know any Sans' you want to see coming up as I still have a bunch to include, and let me know what you think the soulmarks look like!! Let me know in the comments what you think! Remember you can contact me at http://alex-thinks-about-life.tumblr.com/ especially if you would like to beta!! Thanks for reading! Trash Queen out!


	5. Flowers fall in love too

**Summary for the Chapter:**

> Uh I have no explanation for this, I just hope you enjoy it!

**Notes for the Chapter:**

> Sorry I've been absent for a while, but I have to prepare for Uni! Dahhh I wish I was able to draw but oh well! Here's another trashy update! Uh check the end notes if you're interested in RP? Thanks! Love you guys!! Trash Queen signing off!

You were really hoping that you and Sans might be able to stop the soulmarks soon. You had a new one this morning, and that meant Sans was more agitated than usual. 

You studied it carefully, pulling your skin one way and the other. It was sat next to your left eye, a yellow flower, wrapped around a bone, with a small clock behind the two, the vines covered in smaller flowers which followed the bone of your eye socket. This one would be a lot harder to hide. 

Sans claimed to have no recognition of it, although he did note he wasn’t familiar with all of the alternate universes, only some of the more prominent ones. It was he who had spotted it, although it wasn’t exactly easy to miss, causing him to place his hands on your face, pulling at your face gently, to study the mark which caused you to blush at the close contact between you. Wait what? No, Sans was your best friend. A best friend who you happened to be soul mated with the alternate versions of. You couldn’t deny he was a good friend, although the sight of so many marks angered him, for some reason. You supposed part of him must hold himself responsible despite the fact you had both activated the machine which you assumed to be the root of the problem. 

After the incident with Purple and Cherry, Sans had moved in with you, refusing to leave you alone vulnerable to attack from more ‘psycho versions of himself.’ You couldn’t deny it was nice, having him close by set your soul at ease, though he refused to let you take the sofa. So naturally you ended up sharing the bed. He had to take extra care to not let you see his mark. 

It was awkward at first, but you soon realised the necessity of it. if Sans was left alone in the lounge he would spend the whole night looking for new universes which could be acting up. You admired his dedication to the research, and you were flattered he was taking it so seriously, but you were worried for your friend. 

Over the course of the week you managed to fall into a routine, Sans could work until 10 but after that he had to come and relax with you. You would usually drink a hot chocolate before heading for bed. So you invited Sans to join your routine, and he happily acquiesced. It was a cute sight, him sipping from a large mug, heat rising from the chocolate steaming up his glasses, and cream smeared above his teeth. It made you want to coo and…something else. You weren’t sure what the emotion was exactly, it felt odd and fractured. Repressed. Imprisoned. 

In the beginning, when you and Sans settled into bed, he would usually lie as far as way from you as possible. Eventually you coaxed him a bit closer, although he was hesitant. It was somewhat like talking to a rabbit, one wrong move and you would scare him away. You began to realise how bold he had been due to his intoxication when he originally slept with you. So when his arms coiled around your waist, coming to rest over your stomach, it was unexpected to say the least. You stiffened at the odd sensation, but relaxed almost instantly.

“Sorry.” Came Sans’ apologetic voice in your ear as he moved to release you.

“No, no its okay. I just wasn’t expecting it.” You replied. 

Now most nights ended like that, you and Sans wrapped around each other. 

You were both somewhat on edge, after the inevitable appearance of another Sans was looming. But you couldn’t say you were expecting a knock on the door, three soft quiet raps, as though the knocker was hoping you wouldn’t hear them. Startled, you lifted your head from Sans’ shoulder where you had been resting, still not fully awake and alert. 

Your skeleton companion on the other hand seemed far more conscious. 

Cautiously you made your way over the floor towards the doorway. You reached out and opened it quickly. Sans was positioned on the other side of the door, prepared to help. 

In the doorway, stood Red. A skeleton with a black jacket, hood lined with faux fur, black shorts with yellow stripes, shoes in red and black with yellow laces, the same red eyes cast towards the floor and golden dog tooth. But…something was different. Something in the way he carried himself wasn’t the same confident manner of Red. His manner was shyer, sadder somehow. The usual grin was curved downwards. His turtleneck was red, but the collar was striped with black. You quickly realised this was due to a scarf. From his neck hung a 4 pointed star. 

“Hey uh, sorry fer disturbin’ ya this early an’ all, but, I’m not sure where I am? Could ya help me?” He asked, eyes fixed firmly on the floor. At least the gruff manner of speaking was the same.

“Red…?” You asked hesitantly, not sure how the skeleton could have changed so much in less than a month.

He glanced up at the sound of your voice and seemed to do a double take before taking a step back. “F-frisk? Sweetheart...Holy…how?” Scarlet tears welled up in the corner of his eyes as he reached out a hand and it came to rest on your cheek. His touch was soft, delicate as though you might break under his touch.

“I’m sorry?” You asked, unfamiliar with this greeting. He pressed his eyes shut, and shook his head, blinking away the tears as they trickled down his cheeks. He traced a hand gingerly over your eyes, the bridge of your nose. 

“The flowers…they’re gone.” He whispered, as though in awe, reaching his arms out as though to embrace you, walking in a direct line.

Sans grabbed you by the collar and pulled you backwards causing Red to charge into the apartment. Then he shut the door and motioned for you to stand next to it. 

“Stay there.” He commanded and you nodded uncertainly. Red had skidded to a stop, and was looking confused. His eyes searched the room, almost desperately taking in Sans, and then gliding past him to you. he seemed relieved but so bewildered. 

“Sweetheart? I don’t…did I do somethin’ wrong?” He asked, his expression so vulnerable and confused it made your heart break a little. 

Sans made to stand in front of you, you peering over his shoulder. “Look here buddy, I don’t know which version of me you are, or why you think Y/N is Frisk, but what I do know is you’re leavin’. Pronto.” Red’s eyes flickered to Sans and back to you, unable to keep them away from your features, as though he was memorising them. 

“Y…Y/N? Oh…. I see. So they weren’t ever Frisk.” The realisation seemed to dawn on his face, and pain seemed to dominate his features. He collapsed in a defeated pile on the floor. You felt a pang in your chest and you ran stepped out from behind Sans, towards Red. 

“I’m sorry.” You spoke softly. His head jerked up and he looked surprised. 

“What for? ‘s not ya fault.” He murmured quietly. 

You still felt guilt swelling in your throat. “Maybe not, but it’s a way of sympathising I suppose.”

“I don’t need ya sympathy.” He sighed, a sharp edge to his tone, which caused Sans to narrow his eyes at him. 

“Uh…hey. What do we call you?” You asked the skeleton as he studied the floor in detail. 

He shrugged. “Don’ care.” 

You bit your lip and cast a look at Sans, begging for help. He just shrugged at you. You were struck with an idea, and you walked over to the skeleton collapsed on the floor. Sans caught your arm as you passed. 

“Are you mad? We don’t know who this guy is or which universe he comes from! He could be dangerous!” 

“Maybe he is.” You hissed back. “But right now, he looks like he needs help.” You marched over and slid to the floor next to the skeleton. Neither of you spoke for a moment.

“What was Frisk like?” You asked softly. 

He choked back a laugh. “Frisk? They were…incredible. So determined. So perseverant. So kind. I-We had never seen nothin’ like them before. It was their mission to befrien’ everyone in the Underground and nothin’ was gonna stop ‘em. Not even death. Asgore, they died a lot. But they always came back. They were always so polite an’ kind. If ya asked ‘em why, they’d say ‘sometimes kindness is all you can give.’ S-stars, ‘m sorry, I just miss ‘em so much.” The skeleton began to sob, loud, heartbroken tears rolling in thick successive streams down his rounded face. 

You sat there, unsure what to do. You were never good with people crying. But then an idea began to form in your head which could help the skeleton whom you decided to call Starberry. 

It took the three of you about 10 minutes to get to the beach. You were lucky to live so close to one at the edge of your town. 

Starberry was looking out at the sea, the clear light blue waves crashing against the shore every few moments. He seemed more relaxed though he still looked confused. You were glad you had waited until the evening to do this. The orange sky was streaked with dark purple.  
“What are we doin’ here?” Sans asked you.

You knelt at the shoreline in the sand, swinging your backpack from your shoulders. “I…had a friend once, who told me about a ritual her family did to remember their loved ones.” You turned to Sans and Starberry, holding a flower with a candle attached to the centre. “I thought…maybe we could use them together for Frisk. That is…if you want to?” You asked, hesitantly holding out a flower to Starberry. 

He traced it with his eyes for a second before offering you a smile. “I’d like that.” He extended his arm and gently took the flower from you. You turned and offered the flower to Sans, who took it without a word, but gave you a supportive smile. You released a breath with a slow exhale and then grabbed the matches from your backpack. You struck them against the side of the box, once, twice and voila! The warm heat from the match soothed you and the soft light cast a spotlight around you and your friends. 

You lowered the match into the flower and lit the candles. Quickly you shook the match to extinguish the fire before it burnt your fingers. You held your own in your hands, the flame flickering delicately in the flower. 

You beckoned them forwards as you strode forwards into the sea. 

“Uh Y/N? What are ya doing’?” Starberry asked. 

“You can’t put them too close to the shore or the waves will just keep bringing it back. We have to go further out where the currents are stronger. Watch.” You walked a bit further, until the water was up to your waist. The skeletons looked at each other and shrugged, following you into the ocean. 

You gently placed the glowing flower on the surface of the water, waiting until it was tugged from your hands by the water. You all watched as the flowers headed out to sea. You glanced at Starberry’s face and saw it was composed into a contented smile. 

Impulsively you threw your arms around him. He stiffened initially, but then he held you tightly, like if he let go you would cease to be real.

“Thank you Y/N.” He whispered.

Mournfully Sans watched as the two of you embraced, illuminated by the flickering remains of the light from the candles until the flowers drifted away and were gone forever.

**Notes for the Chapter:**

> Possible FF Sans in next chapter too? Hey guys, just thought I'd add this here. So me and one of my friends decided we'd like to do an Undertale rp, and we were wondering if any of you guys would be interested! Well, it's not going to be hugely serious, just for fun, so let me know what you think in the comments!! I'm thinking of either setting up a blog on tumblr or a skype group so let me know which you think would work better!!!!!


	6. Note

Hey guys, so I really want to update this and by the sounds of it you guys want that too. But I'm stuck in a rut, so you guys should help me out! Send me your plot ideas and you can even help me write the next chapter! 

Also if you guys like Steven Universe, check out my friends fanfiction here -https://archiveofourown.org/works/9551450. It would really help them out! Thanks guys!   
Kisses from Trash Queen x

**Author's Note:**

> Oh poor Sans!!! Let me know if you want to see more of this...Maybe with more Sans'?


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